CVE-2021-3782

Severity: medium (CVSS 6.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2022-09-23 · updated 2026-06-17
Weakness: CWE-190

Description

An internal reference count is held on the buffer pool, incremented every time a new buffer is created from the pool. The reference count is maintained as an int; on LP64 systems this can cause the reference count to overflow if the client creates a large number of wl_shm buffer objects, or if it can coerce the server to create a large number of external references to the buffer storage. With the reference count overflowing, a use-after-free can be constructed on the wl_shm_pool tracking structure, where values may be incremented or decremented; it may also be possible to construct a limited oracle to leak 4 bytes of server-side memory to the attacking client at a time.

Affected products

wayland: before 1.20.91 — fixed in 1.20.91

How to fix

Upgrade to a fixed version: wayland 1.20.91. Check the vendor advisory for mitigations.

References

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